Heat processing apparatus and heat processing method

ABSTRACT

A heat processing apparatus includes a heating plate configured to heat the substrate; a cover configured to surround a space above the heating plate; an exhaust gas flow forming mechanism configured to exhaust gas inside the cover to form exhaust gas flows within the space above the heating plate; a downflow forming mechanism configured to form downflows uniformly supplied onto an upper surface of the substrate placed on the heating plate; and a control mechanism configured to execute mode switching control between a mode arranged to heat the substrate while forming the downflows by the downflow forming mechanism and a mode arranged to heat the substrate while forming the exhaust gas flows by the exhaust gas flow forming mechanism.

CROSS REFERENCE TO RELATED APPLICATION

The present divisional application claims the benefit of priority under35 U.S.C. 120 to application Ser. No. 11/624,404, filed Jan. 18, 2007,and claims the benefit of priority under 35 U.S.C. 119 from JapaneseApplication No. 2006-015926, filed on Jan. 25, 2006. The entire contentsof application Ser. No. 11/624,404 are hereby incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat processing apparatus and heatprocessing method for heating a substrate, which are used formanufacturing semiconductor devices while performing acoating/developing process on a substrate, such as a semiconductorwafer.

2. Description of the Related Art

In a photolithography step for semiconductor devices, a resist isapplied onto a semiconductor wafer (which will be simply referred to as“wafer” hereinafter) to form a resist film. Then, the resist film issubjected to a light exposure process in accordance with a predeterminedcircuit pattern. Then, the light-exposed pattern thus formed issubjected to a developing process to form a circuit pattern on theresist film.

In a photolithography step of this type, various heat processes areperformed, such as a heat process (pre-baking) performed subsequently tocoating of a resist or a chemical solution for, e.g., a BARC, a heatprocess (post exposure baking) performed subsequently to light exposure,and a heat process (post baking) performed subsequently to development.

In general, these heat processes are performed by a heat processingapparatus (hot plate unit) provided with a heating plate (hot plate)heated by a heater. Conventionally, in a heat processing apparatus ofthis type, the following gas flow control is typically adopted toperform a heat process on a wafer as uniform as possible. Specifically,during the heat process, the heating plate is covered with a cover, inwhich gas flows are formed from around the heating plate toward thecenter, and gas is exhausted upward from the center of the cover.

In recent years, circuit patters of semiconductor devices show rapidprogress in decreasing the line width, in decreasing the size, and inincreasing the degree of integration, which requires the processuniformity of heat processes to be further improved. However, by use ofthe gas flow control described above, it has become difficult to attaindesired process uniformity, particularly uniformity concerning gas flowsrelative to a wafer, which is necessary to uniformize criticaldimensions (CD). Accordingly, it is required to provide a technique forperforming a heat process with higher uniformity. As a technique forrealizing a heat process with higher uniformity, Jpn. Pat. Appln. KOKAIPublication No. 2003-318091 discloses a technique for performing a heatprocess while supplying gas flows from above uniformly onto the entiresurface of a substrate. According to this technique, since the gas flowsuniformly strike the entire surface of the substrate, such as a wafer,it is possible to improve the process uniformity, particularlyuniformity in the film thickness of a coating film.

However, devices for the next generation require very minute patternswith a CD value of 50 nm or less, in which even slight dust may cause adefect. Accordingly, it is necessary to swiftly remove sublimedsubstances and so forth generated by a heat process. In this respect,the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No.2003-318091 mentioned above cannot sufficiently remove sublimedsubstances and so forth, and thus it may deteriorate the yield ofproducts. Particularly, such deterioration in the yield due to sublimedsubstances is easily caused in a coating film for argon fluoride (ArF)having a short wavelength. This coating film is used for furtherimproving the resolving power of light exposure in accordance with a CDfor the next generation.

Further, depending on coating films, heat processes of this kind includeprocesses that should give weight to CD uniformity and processes thatshould give weight to an improvement in the product yield by removingsubstances, such as sublimed substances, that generate dust. However,the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No.2003-318091 mentioned above cannot address the latter type. Accordingly,there is a great demand for a heat processing technique that can addressthese two types.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a heat processingapparatus and heat processing method that can realize both of highuniformity and high product yield.

An alternative object of the present invention is to provide a heatprocessing apparatus that can perform both of a process that givesweight to high uniformity and a process that gives weight to highproduct yield.

A further alternative object of the present invention is to provide acomputer readable storage medium that stores a control program forexecuting the heat processing method described above.

According to a first aspect of the present invention, there is provideda heat processing apparatus for performing a heat process on asubstrate, the apparatus comprising: a heating plate configured to heatthe substrate; a cover configured to surround a space above the heatingplate; a first gas flow forming mechanism configured to form gas flowsmainly arranged to realize a uniform heat process, within the spaceabove the heating plate; and a second gas flow forming mechanismconfigured to form gas flows mainly arranged to exhaust and remove gasand/or sublimed substances generated from the substrate, within thespace above the heating plate, wherein the first gas flow formingmechanism and the second gas flow forming mechanism are selectivelyswitchable therebetween.

According to a second aspect of the present invention, there is provideda heat processing apparatus for performing a heat process on asubstrate, the apparatus comprising: a heating plate configured to heatthe substrate; a cover configured to surround a space above the heatingplate; a first gas flow forming mechanism configured to form gas flowsmainly arranged to realize a uniform heat process, within the spaceabove the heating plate; a second gas flow forming mechanism configuredto form gas flows mainly arranged to exhaust and remove gas and/orsublimed substances generated from the substrate, within the space abovethe heating plate; and a control mechanism configured to execute modeswitching control between a mode arranged to heat the substrate whileforming the gas flows by the first gas flow forming mechanism and a modearranged to heat the substrate while forming the gas flows by the secondgas flow forming mechanism.

[There are Deleted Portions.]

In the first or second aspect of the present invention, the first gasflow forming mechanism may be configured to form downflows uniformlysupplied onto an upper surface of the substrate placed on the heatingplate. The second gas flow forming mechanism may be configured toexhaust the space above the heating plate to form gas flows along thesubstrate.

[There are Deleted Portions.]

According to a third aspect of the present invention, there is provideda heat processing apparatus for performing a heat process on asubstrate, the apparatus comprising: a heating plate configured to heatthe substrate; a cover configured to surround a space above the heatingplate; an exhaust gas flow forming mechanism configured to exhaust gasinside the cover to form exhaust gas flows within the space above theheating plate; and a downflow forming mechanism configured to formdownflows uniformly supplied onto an upper surface of the substrateplaced on the heating plate, wherein modes are switchable between a modearranged to heat the substrate while forming the downflows by thedownflow forming mechanism and a mode arranged to heat the substratewhile forming the exhaust gas flows by the exhaust gas flow formingmechanism.

[There are Deleted Portions.]

In the third aspect of the present invention, the downflow formingmechanism may comprise a gas supply mechanism configured to supply a gasas a shower onto the upper surface of the substrate from a ceiling wallof the cover, and a periphery exhaust mechanism configured to exhaustgas outwardly in radial directions from the substrate. The exhaust gasflow forming mechanism may comprise an exhaust portion located at thecenter of a ceiling wall of the cover and a gas feed portion configuredto supply a gas from around the substrate into the space above theheating plate, such that a gas is supplied from the gas feed portion andis exhausted from the exhaust portion to form exhaust gas flows from aperiphery of the substrate toward a center thereof, within the spaceabove the heating plate. Alternatively, the exhaust gas flow formingmechanism may comprise a gas feed portion and an exhaust portionrespectively located on opposite sides of the space above the heatingplate, such that a gas is supplied from the gas feed portion and isexhausted from the exhaust portion to form exhaust gas flows from oneside of the substrate toward an opposite side thereof, within the spaceabove the heating plate.

According to a fifth aspect of the present invention, there is provideda heat processing method for performing a heat process by use of a heatprocessing apparatus, which comprises a heating plate configured to heatthe substrate, a cover configured to surround a space above the heatingplate, a first gas flow forming mechanism configured to form gas flowsmainly arranged to realize a uniform heat process, within the spaceabove the heating plate, and a second gas flow forming mechanismconfigured to form gas flows mainly arranged to exhaust and remove gasand/or sublimed substances generated from the substrate, within thespace above the heating plate,

the method comprising: heating the substrate while forming the gas flowsby the first gas flow forming mechanism; and heating the substrate whileforming the gas flows by the second gas flow forming mechanism.

In the fifth aspect of the present invention, the method preferablycomprises first heating the substrate while forming the gas flows by thefirst gas flow forming mechanism, and then heating the substrate whileforming the gas flows by the second gas flow forming mechanism. Further,said heating the substrate while forming the gas flows by the first gasflow forming mechanism may be performed while forming downflowsuniformly supplied onto an upper surface of the substrate placed on theheating plate. Further, said heating the substrate while forming the gasflows by the second gas flow forming mechanism may be performed whileexhausting gas from the space above the heating plate to form gas flowsalong the substrate.

[There are Deleted Portions.]

According to a sixth aspect of the present invention, there is provideda heat processing method for performing a heat process by use of a heatprocessing apparatus, which comprises a heating plate configured to heatthe substrate, a cover configured to surround a space above the heatingplate, an exhaust gas flow forming mechanism configured to exhaust anatmosphere inside the cover from above or sidewise to form exhaust gasflows within the space above the heating plate, and a downflow formingmechanism configured to form downflows uniformly supplied onto an uppersurface of the substrate placed on the heating plate,

the method comprising: heating the substrate while forming the downflowsby the downflow forming mechanism; and heating the substrate whileforming the exhaust gas flows by the exhaust gas flow forming mechanismwithin the space above the heating plate.

[There are Deleted Portions.]

In the sixth aspect of the present invention, said heating the substratewhile forming the downflows by the downflow forming mechanism maycomprise forming the downflows by supplying a gas as a shower onto theupper surface of the substrate from a ceiling wall of the cover whileexhausting gas outwardly in radial directions from the substrate.Further, said heating the substrate while forming the exhaust gas flowsby the exhaust gas flow forming mechanism within the space above theheating plate may be performed while forming the exhaust gas flows froma periphery of the substrate toward a center thereof, within the spaceabove the heating plate. Alternatively, said heating the substrate whileforming the exhaust gas flows by the exhaust gas flow forming mechanismwithin the space above the heating plate may be performed while formingthe exhaust gas flows from one side of the substrate toward an oppositeside thereof, within the space above the heating plate.

[There are Deleted Portions.]

According to a seventh aspect of the present invention, there isprovided a computer readable storage medium that stores a controlprogram for execution on a computer used for a heat processingapparatus, which comprises a heating plate configured to heat thesubstrate, a cover configured to surround a space above the heatingplate, a first gas flow forming mechanism configured to form gas flowsmainly arranged to realize a uniform heat process, within the spaceabove the heating plate, and a second gas flow forming mechanismconfigured to form gas flows mainly arranged to exhaust and remove gasand/or sublimed substances generated from the substrate, within thespace above the heating plate, wherein the control program, whenexecuted, causes the computer to control the heat processing apparatusto conduct a heat processing method comprising: heating the substratewhile forming the gas flows by the first gas flow forming mechanism; andheating the substrate while forming the gas flows by the second gas flowforming mechanism.

According to an eighth aspect of the present invention, there isprovided a computer readable storage medium that stores a controlprogram for execution on a computer used for a heat processingapparatus, which comprises a heating plate configured to heat thesubstrate, a cover configured to surround a space above the heatingplate, an exhaust gas flow forming mechanism configured to exhaust anatmosphere inside the cover from above or sidewise to form exhaust gasflows within the space above the heating plate, and a downflow formingmechanism configured to form downflows uniformly supplied onto an uppersurface of the substrate placed on the heating plate, wherein thecontrol program, when executed, causes the computer to control the heatprocessing apparatus to conduct a heat processing method comprising:heating the substrate while forming the downflows by the downflowforming mechanism; and heating the substrate while forming the exhaustgas flows by the exhaust gas flow forming mechanism within the spaceabove the heating plate.

According to the present invention, there is provided a heat processingapparatus comprising: a first gas flow forming mechanism configured toform gas flows mainly arranged to realize a uniform heat process, withinthe space above the heating plate; and a second gas flow formingmechanism configured to form gas flows mainly arranged to exhaust andremove gas and/or sublimed substances generated from the substrate,within the space above the heating plate, wherein the first gas flowforming mechanism and the second gas flow forming mechanism areselectively switchable therebetween. More specifically, there isprovided a heat processing apparatus comprising: an exhaust gas flowforming mechanism configured to exhaust gas inside the cover to formexhaust gas flows within the space above the heating plate; and adownflow forming mechanism configured to form downflows uniformlysupplied onto an upper surface of the substrate placed on the heatingplate, wherein modes are switchable between a mode arranged to heat thesubstrate while forming the downflows by the downflow forming mechanismand a mode arranged to heat the substrate while forming the exhaust gasflows by the exhaust gas flow forming mechanism. Consequently, it ispossible to perform both of a process that gives weight to highuniformity and a process that gives weight to high product yield, inaccordance with a substrate.

Further, since the apparatus is controlled to switch these modestherebetween, it is possible to serially perform a process that givesweight to high uniformity and a process that gives weight to highproduct yield, thereby realizing both of high uniformity and highproduct yield.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a plan view showing the entire structure of a resistcoating/developing system for semiconductor wafers, which is providedwith a heat processing unit according to an embodiment of the presentinvention;

FIG. 2 is a front view of the resist coating/developing system shown inFIG. 1;

FIG. 3 is a back view of the resist coating/developing system shown inFIG. 1;

FIG. 4 is a perspective view schematically showing the structure of amain wafer transfer unit used in the resist coating/developing systemshown in FIG. 1;

FIG. 5 is a block diagram showing a control system used in the resistcoating/developing system shown in FIG. 1;

FIG. 6 is a sectional view showing a heat processing unit according toan embodiment of the present invention;

FIG. 7 is an enlarged sectional view showing a heating section used inthe heat processing unit according to an embodiment of the presentinvention;

FIG. 8 is a perspective view showing the cover of the heating sectionused in the heat processing unit according to an embodiment of thepresent invention;

FIG. 9 is a plan view schematically showing the interior of the heatprocessing unit according to an embodiment of the present invention;

FIGS. 10A and 10B are views schematically showing the heat processingunit according to an embodiment of the present invention, set in a firstmode and a second mode, respectively;

FIG. 11 is a flowchart showing a heat processing method performed in theheat processing unit according to an embodiment of the presentinvention;

FIGS. 12A to 12C are views schematically showing the heat processingunit according to an embodiment of the present invention, to explainprocedures for transferring a wafer to a cooling plate after a heatprocess;

FIG. 13 is an enlarged sectional view showing a heating section used ina heat processing unit according to an alternative embodiment of thepresent invention;

FIG. 14 is a sectional plan view schematically showing the heatingsection used in the heat processing unit according to an alternativeembodiment of the present invention; and

FIGS. 15A and 15B are views schematically showing the heat processingunit according to an alternative embodiment of the present invention,set in a first mode and a second mode, respectively.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will now be described withreference to the accompanying drawings. FIG. 1 is a plan viewschematically showing a resist coating/developing system forsemiconductor wafers, which is provided with a heat processing unitaccording to an embodiment of the present invention. FIGS. 2 and 3 are afront view and a back view, respectively, of the resistcoating/developing system shown in FIG. 1.

This resist coating/developing system 1 includes a transfer station usedas a cassette station 11, a process station 12 comprising a plurality ofprocessing units, and an interface station 13 located adjacent to theprocess station 12 and configured to transfer wafers W between a lightexposure apparatus 14 and the process station 12.

The cassette station 11 is used such that wafer cassettes (CR) aretransferred thereto from other systems, wherein each of these wafercassettes (CR) stores a plurality of wafers W to be processed in theresist coating/developing system 1. The cassette station 11 is alsoarranged such that wafer cassettes (CR) are transferred therefrom toother systems, wherein each of these wafer cassettes (CR) stores wafersW processed in the resist coating/developing system 1. Further, thecassette station 11 is used to transfer wafers W between the wafercassettes (CR) and process station 12.

As shown in FIG. 1, the cassette station 11 includes a cassette table 20having a plurality of (five in FIG. 1) positioning projections 20 aformed thereon in a row in an X-direction. A wafer cassette (CR) isplaced at each of the projections 20 a such that its wafer transfer portfaces the process station 12.

The cassette station 11 is provided with a wafer transfer mechanism 21located between the cassette table 20 and process station 12. This wafertransfer mechanism 21 includes a wafer transfer pick 21 a, which ismovable in a cassette array direction (X-direction) and in a wafer arraydirection (Z-direction) of the wafers W stored in each wafer cassette(CR), and is further rotatable in a O-direction show in FIG. 1. With thearrangement described above, the wafer transfer pick 21 a can access anyone of the wafer cassettes (CR), and also can access a transition unit(TRS-G3) located in a third processing unit group G3 of the processstation 12 described later.

On the front side of the system, the process station 12 includes a firstprocessing unit group G1 and a second processing unit group G2 arrayedin this order from the cassette station 11. Further, on the rear side ofthe system, the process station 12 includes a third processing unitgroup G3, a fourth processing unit group G4, and a fifth processing unitgroup G5 arrayed in this order from the cassette station 11. A firstmain transfer section A1 is interposed between the third processing unitgroup G3 and fourth processing unit group G4. A second main transfersection A2 is interposed between the fourth processing unit group G4 andfifth processing unit group G5. A sixth processing unit group G6 islocated on the rear side of the first main transfer section A1. Aseventh processing unit group G7 is located on the rear side of thesecond main transfer section A2.

As shown in FIGS. 1 and 2, the first processing unit group G1 includesfive processing units of the spinner type stacked one on the other,which are used as liquid supply units each for performing apredetermined process on a wafer W placed on a spin chuck SP inside acup (CP). For example, the five processing units are formed of threeresist coating units (COT) and two bottom coating units (BARC) forforming an anti-reflective coating that prevents reflection of lightduring light exposure. The second processing unit group G2 includes fiveprocessing units of the spinner type, such as development units (DEV),stacked one on the other.

The third processing unit group G3 includes ten units or the likestacked one on the other, as shown in FIG. 3, which are formed of atemperature adjusting unit (TCP), a transition unit (TRS-G3), a sparespace V, three high-precision temperature adjusting units (CPL-G3), andfour high-temperature heat processing units (BAKE) in this order frombelow. The transition unit (TRS-G3) is used as a portion fortransferring a wafer W between the cassette station 11 and first maintransfer section A1. The spare space V is used for attaching a desiredprocessing unit of the oven type, such as a processing unit of the oventype for performing a predetermined process on a wafer W placed on aworktable. Each of the high-precision temperature adjusting units(CPL-G3) is used for performing a heat process on a wafer W at atemperature controlled with high precision. Each of the high-temperatureheat processing units (BAKE) is used for performing a predetermined heatprocess on a wafer W.

The fourth processing unit group G4 includes ten units or the likestacked one on the other, as shown in FIG. 3, which are formed of ahigh-precision temperature adjusting unit (CPL-G4), four pre-bakingunits (PAB), and five post baking units (POST) in this order from below.Each of the pre-baking units (PAB) is used for performing a heat processon a wafer W after resist coating. Each of the post baking units (POST)is used for performing a heat process on a wafer W after a developingprocess.

The fifth processing unit group G5 includes ten units or the likestacked one on the other, as shown in FIG. 3, which are formed of fourhigh-precision temperature adjusting units (CPL-G5) and six postexposure baking units (PEB) in this order from below. Each of the postexposure baking units (PEB) is used for performing a heat process on awafer W after light exposure and before development.

The high-temperature heat processing units (BAKE), pre-baking units(PAB), post baking units (POST), and post exposure baking units (PEB)located in the third to fifth processing unit groups G3 to G5 have thesame structure, as described later, which forms a heat processing unitaccording to this embodiment. In the third to fifth processing unitgroups G3 to G5, the number and position of units stacked one on theother are not limited to those shown in the drawings, and they can bearbitrarily preset.

The sixth processing unit group G6 includes four units or the likestacked one on the other, which are formed of two adhesion units (AD)and two heating units (HP) for heating a wafer W in this order frombelow. Each of the adhesion units (AD) may have a mechanism foradjusting the temperature of a wafer W. The seventh processing unitgroup G7 includes two units or the like stacked one on the other, whichare formed of a film thickness measuring unit (FTI) and a peripherylight exposure unit (WEE) in this order from below. The film thicknessmeasuring unit (FTI) is used for measuring the thickness of a resistfilm. The periphery light exposure unit (WEE) is used for performinglight exposure selectively only on the edge portion of a wafer W. Aplurality of periphery light exposure units (WEE) may be used andstacked one the other. Further, on the rear side of the second maintransfer section A2, a heat processing unit, such as a heating unit(HP), may be disposed, as in the rear side of the first main transfersection A1.

The first main transfer section A1 is provided with a first main wafertransfer unit 16, which can selectively access the units located in thefirst processing unit group G1, third processing unit group G3, fourthprocessing unit group G4, and sixth processing unit group G6. The secondmain transfer section A2 is provided with a second main wafer transferunit 17, which can selectively access the units located in the secondprocessing unit group G2, fourth processing unit group G4, fifthprocessing unit group G5, and seventh processing unit group G7.

As shown in FIG. 4, the first main wafer transfer unit 16 includes threearms 7 a, 7 b, and 7 c each for holding a wafer W. These arms 7 a to 7 care movable back and forth along a base plate 52. The base plate 52 isrotatably supported by a support portion 53 and can be rotated by amotor built in the support portion 53. The support portion 53 is movableup and down along support struts 55 extending in the vertical direction.The support struts 55 are respectively provided with sleeves 55 aextending in a vertical direction, while a flange portion 56 laterallyprojected from the support portion 53 slidably engages with sleeves 55a. The support portion 53 can be moved up and down by an elevatingmechanism (not shown) through the flange portion 56. With thisarrangement, the arms 7 a to 7 c of the first main wafer transfer unit16 are movable in the X-direction, Y-direction, and Z-direction, and isrotatable in the X-Y plane. Consequently, as described above, the firstmain wafer transfer unit 16 can selectively access the units located inthe first processing unit group G1, third processing unit group G3,fourth processing unit group G4, and sixth processing unit group G6.

A shield plate 8 is attached between the arm 7 a and arm 7 b to blockoff radiation heat from these arms. Further, a light emitting element(not shown) of a sensor member 59 is located above the distal end of theuppermost arm 7 a, while a light receiving element (not shown) isattached at the distal end of the base plate 52. The light emittingelement and light receiving element constitute an optical sensor toconfirm the presence/absence and protruding of a wafer W on each of thearms 7 a to 7 c. FIG. 4 also shows a wall portion 57 as a part of thehousing of the first main transfer section A1 on the first processingunit group G1 side. The wall portion 57 has window portions 57 a formedtherein, through which a wafer W is transferred to and from therespectively units of the first processing unit group G1. The secondmain wafer transfer unit 17 has the same structure as that of the firstmain wafer transfer unit 16.

A liquid temperature adjusting pump 24 and a duct 28 are located betweenthe first processing unit group G1 and cassette station 11. A liquidtemperature adjusting pump 25 and a duct 29 are located between thesecond processing unit group G2 and interface station 13. The liquidtemperature adjusting pumps 24 and 25 are used for supplyingpredetermined process liquids to the first processing unit group G1 andsecond processing unit group G2, respectively. The ducts 28 and 29 areused for supplying clean air into the processing unit groups G1 to G5from an air conditioner (not shown) located outside the resistcoating/developing system 1.

The first to seventh processing unit groups G1 to G7 are detachable fora maintenance operation. The rear side panel of the process station 12is also detachable or openable. Further, chemical units (CHM) 26 and 27are respectively located below the first processing unit group G1 andsecond processing unit group G2 and are used for supplying predeterminedprocess liquids to the first processing unit group G1 and secondprocessing unit group G2.

The interface station 13 comprises a first interface station 13 a on theprocess station 12 side, and a second interface station 13 b on thelight exposure apparatus 14 side. The first interface station 13 a isprovided with a first wafer transfer device 62 that faces an opening ofthe fifth processing unit group G5. The second interface station 13 b isprovided with a second wafer transfer device 63 movable in theX-direction.

An eighth processing unit group G8 is located on the rear side of thefirst wafer transfer device 62. The eighth processing unit group G8includes units or the like stacked one on the other, as shown in FIG. 3,which are formed of an outgoing buffer cassette (OUTBR), an incomingbuffer cassette (INBR), and a periphery light exposure unit (WEE) inthis order from below. The outgoing buffer cassette (OUTBR) is used fortemporarily placing wafers W transferred from the light exposureapparatus 14. The incoming buffer cassette (INBR) is used fortemporarily placing wafers W to be transferred into the light exposureapparatus 14. Each of the incoming buffer cassette (INBR) and outgoingbuffer cassette (OUTBR) is configured to accommodate a plurality of,e.g., 25, wafers W. Further, a ninth processing unit group G9 is locatedon the front side of the first wafer transfer device 62. The ninthprocessing unit group G9 includes units or the like stacked one on theother, as shown in FIG. 2, which are formed of two high-precisiontemperature adjusting units (CPL-G9) and a transition unit (TRS-G9) inthis order from below.

The first wafer transfer device 62 includes a wafer transfer fork 62 a,which is movable in the Z-direction, rotatable in the O-direction, andfurther movable back and forth in the X-Y plane. This fork 62 a canselectively access the units located in the fifth processing unit groupG5, eighth processing unit group G8, and ninth processing unit group G9,so that wafers W can be transferred among these units.

Similarly, the second wafer transfer device 63 includes a wafer transferfork 63 a, which is movable in the X-direction and Z-direction,rotatable in the θ-direction, and further movable back and forth in theX-Y plane. This fork 63 a can selectively access the units located inthe ninth processing unit group G9, and an incoming stage 14 a and anoutgoing stage 14 b of the light exposure apparatus 14, so that wafers Wcan be transferred among these portions.

As shown in FIG. 2, a central control section 19 is located below thecassette station 11 and is used for controlling this resistcoating/developing system 1, as a whole. As shown in FIG. 5, thiscentral control section 19 includes a process controller 101 comprisinga CPU for controlling the respective components included in the resistcoating/developing system 1, such as the processing units and transfermechanisms. The process controller 101 is connected to the userinterface 102, which includes, e.g., a keyboard and a display, whereinthe keyboard is used for a process operator to input commands foroperating the respective components in the resist coating/developingsystem 1, and the display is used for showing visualized images of theoperational status of the respective components in the resistcoating/developing system 1. Further, the process controller 101 isconnected to the storage portion 103, which stores recipes with controlprograms and process condition data recorded therein, for realizingvarious processes performed in the resist coating/developing system 1under the control of the process controller 101.

A required recipe is retrieved from the storage portion 103 and executedby the process controller 101 in accordance with an instruction or thelike input through the user interface 102. Consequently, each of variouspredetermined processes is performed in the resist coating/developingsystem 1 under the control of the process controller 101. Recipes may bestored in a computer readable storage medium, such as a CD-ROM, harddisk, flexible disk, or nonvolatile memory. Further, recipes may beutilized on-line, while it is transmitted from a suitable apparatusthrough, e.g., a dedicated line, as needed. Each of the respectivecomponents is provided with its own subordinate control section, whichcontrol the operation of the corresponding component in accordance withinstructions transmitted from the process controller 101.

In the resist coating/developing system 1 arranged as described above,unprocessed wafers W are taken out one by one from a wafer cassette (CR)by the wafer transfer mechanism 21. A wafer W thus taken out istransferred by the wafer transfer mechanism 21 into the transition unit(TRS-G3) located in the processing unit group G3 of the process station12. Then, the wafer W receives a temperature adjusting treatment in thetemperature adjusting unit (TCP). Then, the wafer W is sequentiallysubjected to formation of an anti-reflective coating performed by one ofthe bottom coating units (BARC) of the first processing unit group G1, aheat process performed by one of the heating units (HP), and a bakingprocess performed by one of the high-temperature heat processing units(BAKE). Before the formation of an anti-reflective coating performed byone of the bottom coating units (BARC), the wafer W may be subjected toan adhesion process performed by one of the adhesion units (AD). Then,the wafer W receives a temperature adjusting treatment in thehigh-precision temperature adjusting unit (CPL-G4). Then, the wafer W istransferred into one of the resist coating unit (COT) located in thefirst processing unit group G1, in which the wafer W is subjected to aprocess for applying a resist liquid. Thereafter, the wafer W issequentially subjected to a pre-baking process performed by one of thepre-baking units (PAB) located in the fourth processing unit group G4,and a periphery light exposure process performed by one of the peripherylight exposure units (WEE). Then, the wafer W receives a temperatureadjusting treatment in the high-precision temperature adjusting unit(CPL-G4) or the like. Thereafter, the wafer W is transferred by thesecond wafer transfer device 63 into the light exposure apparatus 14.After the wafer W is subjected to a light exposure process performed bythe light exposure apparatus 14, the wafer W is transferred by thesecond wafer transfer device 63 into the transition unit (TRS-G9). Then,the wafer W is transferred by the first wafer transfer device 62 intoone of the post exposure baking units (PEB) located in the fifthprocessing unit group G5, in which the wafer W is subjected to a postexposure baking process. Further, the wafer W is transferred into one ofthe development units (DEV) located in the second processing unit groupG2, in which the wafer W is subjected to a developing process. Then, thewafer W is subjected to a post baking process performed by the postbaking unit (POST). Then, the wafer W receives a temperature adjustingtreatment in one of the high-precision temperature adjusting units(CPL-G3). Then, the wafer W is transferred by the transition unit(TRS-G3) to a predetermined position in a wafer cassette (CR) placed onthe cassette station 11.

Next, a detailed explanation will be given of the heat processing unitaccording to an embodiment of the present invention. As described above,the high-temperature heat processing units (BAKE), pre-baking units(PAB), post baking units (POST), and post exposure baking units (PEB)have the same structure, which forms a heat processing unit according tothis embodiment, i.e., a heat processing unit (CHP) provided with acooling plate. FIG. 6 is a sectional view showing the heat processingunit according to this embodiment. FIG. 7 is an enlarged sectional viewshowing a heating section used in the heat processing unit. FIG. 8 is aperspective view showing the cover of the heating section used in theheat processing unit. FIG. 9 is a plan view schematically showing theinterior of the heat processing unit.

This heat processing unit (CHP) includes a casing 110, in which aheating section 120 is located on one side, and a cooling section 160 islocated on the other side.

The heating section 120 includes a heating plate 121 like a circularplate for heating a wafer W. The heating plate 121 is supported withinthe inner space of a support member 122 having a compressed circularcylindrical shape opened upward. The upper side of the support member122 is covered with a cover 123 having a compressed circular cylindricalshape opened downward. The cover 123 can be moved up and down by anelevating mechanism (not shown). When the cover 123 is set at the upperposition, the wafer W can be loaded and unloaded to and from the heatingplate 121. When the cover 123 is set at the lower position, the lowerend of the cover 123 comes into close contact with the upper end of thesupport member 122 to form a heat processing space S. The support member122 is fixed on a spacer 124 placed on the bottom of the casing 110.

The heating plate 121 is made of, e.g., aluminum, and is provided withproximity pins 125 on the surface. The wafer W is placed on theproximity pins 125 to be adjacent to the heating plate 121. The heatingplate 121 has an electric heater 126 built therein with a predeterminedpattern. Electricity is applied from a heater power supply 127 to thiselectric heater 126 to set the heating plate 121 at a predeterminedtemperature. The heating temperature is controlled by means of feedbackcontrol using a thermo couple (not shown) located near the surface ofthe heating plate 121.

The heating plate 121 has three through holes 128 formed therein at thecentral portion (only two of them are shown in FIG. 6). Lifter pins 129are respectively inserted in these through holes 128 and are movable upand down to move the wafer W up and down. The lifter pins 129 areattached to a support plate 130 and are moved up and down along with thesupport plate 130 by a cylinder mechanism 131 located below the casing110.

As shown in the enlarged view of FIG. 7, the cover 123 is formed of aceiling wall 123 a and a sidewall 123 b. The ceiling wall 123 a includesan upper plate 132 and a lower plate 133, which define a gas diffusionspace d therebetween. Further, the lower plate 133 of the ceiling wall123 a has a number of gas delivery holes 133 a uniformly distributed. Anexhaust pipe 135 is formed to penetrate the center of the ceiling wall123 a in the vertical direction. The sidewall 123 b of the cover 123 hasa plurality of air intake ports 136 opened on the upper surface andarrayed in an annular direction. A plurality of air feed passages 137are formed in the sidewall 123 b to connect the air intake ports 136 tothe heat processing space S. In place of the air intake ports 136, a gasfeed mechanism for supplying another gas, such as N₂ gas, may be used.

The sidewall 123 b of the cover 123 further has a plurality of gasexhaust ports 138 opened on the inner surface and arrayed along a lowerside of the inner surface. A plurality of vertical exhaust passages 140are formed in the sidewall 123 b such that they extend horizontally fromthe gas exhaust ports 138 and then extend vertically upward. Further, aloop exhaust passage 141 is formed in an upper side of the sidewall 123b, and is connected to the vertical exhaust passages 140.

The ceiling wall 123 a of the cover 123 has a purge gas feed port 142opened on the upper surface, which is connected to a purge gas supplymechanism 144 through a purge gas line 143. The purge gas feed port 142is connected to a loop flow passage 145 formed in the upper plate 132through a flow passage (not shown). A plurality of gas delivery ports145 a are formed below the loop flow passage 145 to deliver the purgegas as a spray. With this arrangement, a purge gas is supplied from thepurge gas supply mechanism 144 through the purge gas feed port 142, flowpassage (not shown), and loop flow passage 145, and is then deliveredfrom the delivery ports 145 a as a spray into the gas diffusion space d.The purge gas thus supplied into the gas diffusion space d is thendelivered from the gas delivery holes 133 a of the lower plate 133 intothe processing space S as a shower. The purge gas line 143 is providedwith a valve 146 for turning on/off the purge gas and adjusting the flowrate thereof. As the purge gas, air or an inactive gas, such as N₂ gasor Ar gas, is preferably used.

At the center of the upper surface of the cover 123, a first exhaustmember 147 a and a second exhaust member 147 b are stacked one on theother in the vertical direction. The exhaust pipe 135 is inserted intothe first exhaust member 147 a on the lower side. The first exhaustmember 147 a is connected to a center exhaust mechanism 149 through anexhaust line 148. The exhaust line 148 is provided with a valve 150 forturning on/off exhaust gas and adjusting the flow rate thereof. Theinner atmosphere of the heat processing space S can be exhausted by thecenter exhaust mechanism 149 through the exhaust passage 35, firstexhaust member 147 a, and exhaust line 148.

A periphery exhaust member 151 is disposed on the upper surface of thecover 123. As shown in FIG. 8, the periphery exhaust member 151 includesvertical portions 151 a located at four positions on the periphery ofthe upper surface of the cover 123, and two horizontal portions 151 beach connecting two of the four vertical portions 151 a. The verticalportions 151 a are connected to the loop exhaust passage 141 of thesidewall 123 b through gas flow passages 141 a. The central portions ofthe two horizontal portions 151 b are connected to each other by thesecond exhaust member 147 b. The central portion of the sidewall of thesecond exhaust member 147 b is connected to a periphery exhaustmechanism 153 through an exhaust line 152. The exhaust line 152 isprovided with a valve 154 for turning on/off exhaust gas and adjustingthe flow rate thereof. The interior of the heat processing space S canbe exhausted by the periphery exhaust mechanism 153 from the exhaustports 138 through the exhaust passages 139 and 140 and loop exhaustpassage 141 and further through the periphery exhaust member 151, secondexhaust member 147 b, and exhaust line 152.

A controller 155 is used for turning on/off and adjusting the valves146, 150, and 154. The controller 155 controls the valves 146, 150, and154 in accordance with instructions transmitted from the processcontroller 101 of the central control section 19 to switch modes betweena first mode shown in FIG. 10A and a second mode shown in FIG. 10B. Inthe first mode, periphery exhaust is set in operation through theexhaust ports 138 while the purge gas is delivered from the gas deliveryholes 133 a, so that a heat process is performed while downflows areuniformly supplied onto the upper surface of the wafer W. In the secondmode, air is drawn from the air intake ports 136 while gas is exhaustedthrough the exhaust pipe 135 at the center of the ceiling wall 123 a ofthe cover 123, so that a heat process is performed, while gas flows(exhaust gas flows) are formed along the wafer W from the periphery ofthe wafer W toward the center, within the heat processing space S. Inother words, the purge gas supply mechanism 144, periphery exhaustmechanism 153, gas delivery holes 133 a, exhaust ports 138, and linesconnecting these portions constitute a first gas flow forming mechanismfor forming gas flows used in the first mode. On the other hand, thecenter exhaust mechanism 149, exhaust pipe 135, air intake ports 136,air feed passages 137, and so forth constitute a second gas flow formingmechanism for forming gas flows used in the second mode.

The cooling section 160 includes a cooling plate 161 and a drivingmechanism 162 for moving the cooling plate 161 in a horizontaldirection. The cooling plate 161 is provided with proximity pins 163thereon, so that the wafer W is placed on the proximity pins 163 to beadjacent to the cooling plate 161 during a cooling process. The drivingmechanism 162 comprises a suitable mechanism, such as a belt mechanismor ball screw mechanism, to move the cooling plate 161 along a guide164. When the wafer W is transferred to and from the heating plate 121,the cooling plate 161 is moved to the heating section 120 side. When acooling or heating process is performed, the cooling plate 161 is set ata reference position shown in FIG. 6. In order to prevent the coolingplate 161 thus moved from interfering with the lifter pins 129, thecooling plate 161 has grooves 165 extending in a transfer direction ofthe cooling plate 161, as shown in FIG. 9.

The cooling plate 161 can be cooled by a cooling mechanism (not shown),and the cooling temperature is controlled by means of feedback controlusing a thermo couple (not shown) located near the surface of thecooling plate 161.

Next, an explanation will be given of a heat processing operationperformed in the heat processing unit arranged as described above, withreference to the flowchart shown in FIG. 11. This explanation will begiven of a heat process performed on a wafer W with a coating liquidapplied thereon.

At first, a wafer W is transferred into the casing 110 (Step 1), forexample, after a predetermined coating liquid is applied thereto, orafter a light exposure process is performed thereon, or after adeveloping process is performed thereon. At this time, the cover 123 isset at the upper position, and the wafer W is transferred onto thelifter pins 129 projecting upward from the heating plate 121. Then, thelifter pins 129 are moved down, so that the wafer W is placed on theproximity pins 125 of the heating plate 121, which is maintained at apredetermined temperature (Step 2). Then, the cover 123 is moved down toclose the heat processing space S.

Then, a heat process is performed in the first mode shown in FIG. 10A(Step 3), in which periphery exhaust is set in operation through theexhaust ports 138 while the purge gas is delivered as a shower from thegas delivery holes 133 a, so that a heat process is performed whiledownflows are uniformly supplied onto the upper surface of the wafer W.In this step, since gas flows are formed as downflows uniformly suppliedover the entire upper surface of the wafer W, the heat process can berealized uniformly over the entire surface of the wafer W, and thus thequality of a resist film or a coating film, such as a BARC, can be madeuniform. Consequently, it is possible to improve the CD uniformity afterdevelopment. In this step, the valve 154 and valve 146 are controlled inaccordance with instructions transmitted from the controller 155, sothat the flow rate of the purge gas supplied from the purge gas supplymechanism 144 and the periphery exhaust rate from the exhaust ports 138are controlled to form desired downflows.

Incidentally, when a wafer with a coating film formed thereon is heated,and particularly a heat process is performed immediately after thecoating film is formed, a lot of gas and/or sublimed substances aregenerated. Conventionally, gas and/or sublimed substances of this kinddo not cause a serious problem in quality. However, with a decrease inCD, e.g., to be 50 nm or less, these substances deposited on a wafer Wmay cause defects, thereby deteriorating the product yield.Particularly, where a baking process is performed on a wafer with a BARCfor ArF formed thereon, a lot of gas and/or sublimed substances of thiskind are generated and affect the process. In this respect, since thefirst mode comprises a step of supplying downflows onto the wafer W,arranged to give weight to uniformity, this mode is basically notsuitable for removing gas and/or sublimed substances. If the first modeis modified to unreasonably increase the exhaust efficiency, theuniformity is impaired.

On the other hand, a center exhaust mode conventionally used is arrangedto form gas flows along a wafer from the periphery of the wafer towardthe center thereof, and to exhaust gas from the center of the ceilingwall. In this case, gas and/or sublimed substances are exhausted andremoved along with the gas flows, so they are scarcely deposited on thewafer. This mode is poor in heat process uniformity, but the followingmatter has been found by studies made by the present inventors.Specifically, this mode, i.e., formation of such gas flows arranged togive weight to gas exhaust, does not impair the quality of a coatingfilm, if this mode is used after the first mode is used for a heatprocess until the quality of the coating film is stabilized.

Accordingly, after the heat process is performed in the first mode, theheat process is performed in the second mode (Step 4), in which gas isexhausted through the exhaust pipe 135 at the center of the ceiling wall123 a of the cover 123. In this step, as shown in FIG. 10B, since gas isexhausted through the exhaust pipe 135, air is drawn from the air intakeports 136 through the air feed passages 137 into the heat processingspace S, so that gas flows (exhaust gas flows) are formed along thewafer W from the periphery of the wafer W toward the center thereof.Consequently, gas and/or sublimed substances generated by the heatprocess are exhausted and removed through the exhaust passage, so theyare scarcely deposited on the wafer W. Further, the gas flows thusformed can effectively remove gas and/or sublimed substances depositedon the wafer W due to the heat process being performed in the firstmode. In this step, the following control is performed in accordancewith instructions transmitted from the controller 155 after the heatprocess is performed in the first mode. Specifically, the valves 146 and154 are closed to stop supply of the purge gas and periphery exhaust, orthese valves are adjusted to form delivery flows from the gas deliveryholes 133 a which can hold off inflow of gas and/or sublimed substancesgenerated from the coating film, while the valve 150 is opened to obtaina predetermined exhaust rate. Consequently, desired gas flows are formedfrom the periphery toward the center. The heat process is completed whenthe second mode is finished.

Where the heat process is a baking process performed on a 300 mm-wafercoated with a BARC for ArF laser, the first mode and second mode inSteps 3 and 4 may employ the following conditions.

Baking temperature: 180 to 220° C. (such as 215° C.)

First Mode

-   -   Purge gas flow rate: 5 L/min    -   Periphery exhaust rate: 5 L/min

Second Mode

-   -   Center exhaust rate: 20 L/min    -   (Purge gas flow rate: 4 L/min (if necessary))

Switching timing from first mode to second mode (total 60 sec): 40 sec

After the heat process is performed on the wafer W for a predeterminedtime, the wafer is placed on the cooling plate 161 and subjected to apredetermined cooling process (Step 5). The procedures for transferringthe wafer at this time will be explained with reference to FIGS. 12A to12C. At first, as shown in FIG. 12A, the wafer W is moved up by thelifter pins 129, and then the cooling plate 161 is moved to a positionabove the heating plate 121. Then, as shown in FIG. 12B, the lifter pins129 is moved down to place the wafer W on the proximity pins 163 of thecooling plate 161. Then, as shown in FIG. 12C, the cooling plate 161 ismoved to the original position and the cooling process is started. Afterthis cooling process, the wafer W is unloaded through a transfer port(not shown) (Step 6). According to this heat processing unit (CHP),since cooling can be performed immediately after heating, wafers do notdiffer in thermal history, so fluctuations of the heat process among thewafers can be smaller.

As described above, the processing unit according to this embodiment isarranged to be switchable between the first mode and second mode.Conventionally, there is no such an idea of switching gas flow formationmodes in heat processing units. In the circumstances, the presentinventors have found for the first time that switching such modes in themiddle of a heat process allows both of high CD uniformity and highproduct yield to be realized.

Next, an explanation will be given of a heat processing unit accordingto an alternative embodiment of the present invention.

FIG. 13 is an enlarged sectional view showing a heating section used ina heat processing unit according to an alternative embodiment. FIG. 14is a sectional plan view schematically showing the heating section. Thisembodiment has the same basic structure as that of the previousembodiment, except that a gas flow formation system of a heating sectionused for the second mode differs from that of the previous embodiment.Accordingly, in FIGS. 13 and 14, the same constituent elements as thosedescribed above are denoted by the same reference numerals used in FIG.7, and their explanation will be omitted.

The heat processing unit according to this embodiment includes a casing,as in the previous embodiment, in which a heating section and a coolingsection are located side by side. The heating section 120′ includes aheating plate 121 structured completely the same as that of the previousembodiment. The heating plate 121 is supported within the inner space ofa support member 222 and the upper side of the support member 222 iscovered with a cover 223. The support member 222 has a compressedrectangular cylindrical shape opened upward, while the cover 223 has acompressed rectangular cylindrical shape opened downward. As in thecover 123 of the previous embodiment, the cover 223 can be moved up anddown. When the cover 223 is set at the upper position, the wafer W canbe loaded and unloaded to and from the heating plate 121. When the cover223 is set at the lower position, the cover 223 cooperates with thesupport member 222 to form a heat processing space S′.

The cover 223 is formed of a ceiling wall 223 a and a sidewall 223 b.The ceiling wall 223 a includes an upper plate 232 and a lower plate233, which define a gas diffusion space d′ therebetween. Further, thelower plate 233 of the ceiling wall 223 a has a number of gas deliveryholes 233 a uniformly distributed.

The sidewall 223 b of the cover 223 further has a plurality of gasexhaust ports 238 opened on the inner surface and arrayed along a lowerside of the inner surface. A plurality of vertical exhaust passages 240are formed in the sidewall 223 b such that they extend horizontally fromthe gas exhaust ports 238 and then extend vertically upward. Further, aloop exhaust passage 241 is formed in an upper side of the sidewall 223b, and is connected to the vertical exhaust passages 240.

Furthermore, the sidewall 223 b of the cover 223 has a gas delivery port242 a formed in a wall portion on the cooling section side at a positionimmediately above the heating plate 121. The gas delivery port 242 a hasa thin and long shape extending in a horizontal direction, and isconnected to a plurality of vertical gas flow passages 243 a verticallyextending in this wall portion of the sidewall 223 b. Further, ahorizontal gas flow passage 244 a extending in a horizontal direction isformed in an upper side of this wall portion, and is connected to thevertical gas flow passages 243 a. On the other hand, the sidewall 223 bof the cover 223 has an exhaust port 242 b formed in a wall portionopposite to the wall portion described above at a position immediatelyabove the heating plate 121. The exhaust port 242 b has a thin and longshape extending in a horizontal direction, and is connected to aplurality of vertical exhaust passages 243 b vertically extending inthis wall portion of the sidewall 223 b. Further, a horizontal exhaustpassage 244 b extending in a horizontal direction is formed in an upperside of this wall portion, and is connected to the vertical exhaustpassages 243 b.

The ceiling wall 223 a of the cover 223 has a purge gas feed port 245opened on the upper surface, which is connected to a purge gas supplymechanism 247 through a purge gas line 246. The purge gas feed port 245is connected to a flow passage 248 formed in the upper plate 232. Apurge gas is supplied from the purge gas supply mechanism 247 throughthe flow passage 248 into a gas feed member 249 located at the center ofan upper side of the gas diffusion space d′, and is then supplied intothe gas diffusion space d′ in radial directions from the gas feed member249. The purge gas thus supplied into the gas diffusion space d′ is thendelivered from the gas delivery holes 233 a of the lower plate 233 intothe processing space S′. The purge gas line 246 is provided with a valve250 for turning on/off the purge gas and adjusting the flow ratethereof.

On the other hand, the loop exhaust passage 241 is connected to exhaustpassages 251 extending upward at a plurality of positions, which areconnected to exhaust lines 252 a above the cover 223. The exhaust lines252 a are connected to a periphery exhaust mechanism 253 through acollecting exhaust line 252 b. The collecting exhaust line 252 b isprovided with a valve 254 for turning on/off exhaust gas and adjustingthe flow rate thereof. The interior of the heat processing space S′ canbe exhausted by the periphery exhaust mechanism 253 from the exhaustports 238 through the vertical exhaust passages 240 and loop exhaustpassage 241 and further through the exhaust lines 252 a and collectingexhaust line 252 b.

Further, the horizontal gas flow passage 244 a is connected to a gasflow passage 255 a extending upward, which is connected to a gas supplyline 256 a above the cover 223. The gas supply line 256 a is connectedto a gas supply mechanism 257 a. The gas supply line 256 a is providedwith a valve 258 a for turning on/off supply gas and adjusting the flowrate thereof. Further, the horizontal exhaust passage 244 b is connectedto an exhaust passage 255 b extending upward, which is connected to anexhaust line 256 b above the cover 223. The exhaust line 256 b isconnected to an exhaust mechanism 257 b. The exhaust line 256 b isprovided with a valve 258 b for turning on/off exhaust gas and adjustingthe flow rate thereof. A predetermined amount of gas, such as air, issupplied from the gas supply mechanism 257 a through the gas flowpassage 255 a, horizontal gas flow passage 244 a, and vertical gas flowpassages 243 a, and is delivered from the gas delivery port 242 a intothe heat processing space S′. On the other hand, the interior of theheat processing space S′ is exhausted, in accordance with the gasdelivery, by the exhaust mechanism 257 b through the exhaust port 242 b,vertical exhaust passages 243 b, horizontal exhaust passage 244 b,exhaust passage 255 b, and exhaust line 256 b. Consequently,unidirectional flows are formed within the heat processing space S′.

A controller 259 is used for turning on/off and adjusting the valves250, 254, 258 a, and 258 b. The controller 259 controls the valves 250,254, 258 a, and 258 b in accordance with instructions transmitted fromthe process controller 101 of the central control section 19 to switchmodes between a first mode shown in FIG. 15A and a second mode shown inFIG. 15B. In the first mode, periphery exhaust is set in operationthrough the exhaust ports 238 while the purge gas is delivered from thegas delivery holes 233 a, so that a heat process is performed whiledownflows are uniformly supplied onto the upper surface of the wafer W.In the second mode, a heat process is performed, while unidirectionalflows are formed from the gas delivery port 242 a to the exhaust port242 b. In this embodiment, the purge gas supply mechanism 247, peripheryexhaust mechanism 253, gas delivery holes 233 a, exhaust ports 238, andlines connecting these portions constitute a first gas flow formingmechanism for forming gas flows used in the first mode. On the otherhand, the gas supply mechanism 257 a, exhaust mechanism 257 b, gasdelivery port 242 a, exhaust port 242 b, and the corresponding flowpassages and lines constitute a second gas flow forming mechanism forforming gas flows used in the second mode.

Also in this embodiment, as in the previous embodiment, a heat processis first performed in the first mode arranged to give weight to theuniformity in film quality. Then, the heat process is performed in thesecond mode arranged to give weight to removal of gas and/or sublimedsubstances generated by the heat process. According to this embodiment,when the heat process is performed in the second mode, unidirectionalflows are formed from the gas delivery port 242 a to the exhaust port242 b. Consequently, gas and/or sublimed substances generated by theheat process are exhausted and removed along with the unidirectionalflows, and thus they are scarcely deposited on the wafer W. Further, theunidirectional flows thus formed can effectively remove gas and/orsublimed substances deposited on the wafer W due to the heat processbeing performed in the first mode. In the previous embodiment, since theexhaust pipe 135 is located directly above the wafer W, dust derivedfrom gas and/or sublimed substances retained or deposited in the exhaustpipe 135 may drop onto the wafer W. In this respect, according to thisembodiment, there is no such a risk. Further, since there is no need toform an exhaust structure on the ceiling wall, the dimension of the heatprocessing unit in the vertical direction can be decreased.

The present invention is not limited to the embodiments described above,and it may be modified in various manners. For example, in theembodiments described above, a heat process is first performed in a modearranged to uniformize the quality of a coating film, and then in a modearranged to remove gas and/or sublimed substances generated from thecoating film. However, there is a coating film that tends to generategas and/or sublimed substances at an early stage. For such case, a heatprocess may be first performed in a mode arranged to remove gas and/orsublimed substances, and then in a mode arranged to uniformize the filmquality. Further, depending on the target substrate, a heat process maybe performed only in a mode arranged to uniformize the quality of acoating film, or only in a mode arranged to remove gas and/or sublimedsubstances generated from a coating film.

In the embodiments described above, the heat processing unit includes acooling plate. However, as a matter of course, the present invention maybe applied to a heat processing unit including no cooling plate.

The present invention may be applied not only to a heat process used inordinary photolithography, but also to a heat process used in a liquidimmersion light exposure process.

In the embodiments described above, the present invention is applied toa heat process performed on a semiconductor wafer with a coating filmformed thereon, but this is not limiting. For example, the presentinvention may be applied to a heat process performed on anothersubstrate, such as a substrate for liquid crystal display devices (LCD),or a heat process performed on a substrate with no coating film formedthereon.

1. A heat processing apparatus comprising: a heating plate configured tosupport and heat a substrate; a cover configured to surround a spaceabove the heating plate; a first gas flow forming mechanism configuredto form first gas flows within the space above the heating plate, thefirst gas flows being downward flows of gas uniformly supplied onto anupper surface of the substrate supported by the heating plate; a secondgas flow forming mechanism configured to form second gas flows withinthe space above the heating plate, the second gas flows being sidewardflows of gas along the upper surface of the substrate supported by theheating plate; and a control mechanism configured to control anoperation of the apparatus and including a computer and a computerreadable non-transitory storage medium that stores a control program,wherein the control program, when executed, causes the computer tocontrol the apparatus to conduct a heat processing sequence, whereinsaid computer is configured to execute a heat process by using theheating plate to heat a target substrate supported by the heating plate,wherein the space above the heating plate is surrounded by the cover,wherein the heat process is performed along with first and second modesof gas flows sequentially set in this order while heating the targetsubstrate by the heating plate, the first mode uses the downward flowsformed by the first gas flow forming mechanism to uniformize the heatprocess over the target substrate, and the second mode uses the sidewardflows formed by the second gas flow forming mechanism while exhaustinggas from the space above the heating plate to exhaust and remove atleast one of gas and sublimed substances generated from the targetsubstrate.
 2. The apparatus according to claim 1, wherein the secondmode uses the sideward flows such that gas is caused to flow from aperiphery of the target substrate toward a center thereof and then to beexhausted upward from the center.
 3. The apparatus according to claim 1,wherein the second mode uses the sideward flows such that gas is causedto flow from one side of the target substrate toward an opposite sidethereof and then to be exhausted from the opposite side.
 4. Theapparatus according to claim 2, wherein the first mode uses the downwardflows such that gas is caused to flow from above onto the targetsubstrate and then to be exhausted toward a periphery of the targetsubstrate.
 5. The apparatus according to claim 3, wherein the first modeuses the downward flows such that gas is caused to flow from above ontothe target substrate and then to be exhausted toward a periphery of thetarget substrate.
 6. The apparatus according to claim 1, wherein thecover includes a number of gas delivery holes formed in a counter platefacing the heating plate and communicating with a gas diffusion spacethat pools a purge gas, periphery exhaust ports opened at positionsaround the heating plate, a center exhaust port opened at a center ofthe counter plate and connected to an exhaust pipe, and gas intake portsopened at positions around the heating plate, such that the first gasflow forming mechanism forms the downward flows by supplying the purgegas from the gas delivery holes toward the substrate supported by theheating plate while exhausting gas on the substrate from the peripheryexhaust ports, and the second gas flow forming mechanism forms thesideward flows by introducing gas from the gas intake ports whileexhausting gas on the substrate supported by the heating plate from thecenter exhaust port.
 7. The apparatus according to claim 1, wherein thecover includes a number of gas delivery holes formed in a counter platefacing the heating plate and communicating with a gas diffusion spacethat pools a purge gas, periphery exhaust ports opened at positionsaround the heating plate, a side delivery port opened at a position onone side around the heating plate, and a side exhaust port opened at aposition on an opposite side around the heating plate, such that thefirst gas flow forming mechanism forms the downward flows by supplyingthe purge gas from the gas delivery holes toward the substrate supportedby the heating plate while exhausting gas on the substrate from theperiphery exhaust ports, and the second gas flow forming mechanism formsthe sideward flows by supplying gas from the side delivery port towardthe substrate supported by the heating plate while exhausting gas on thesubstrate from the side exhaust port.
 8. The apparatus according toclaim 1, wherein the target substrate includes a target film formedthereon and including a resist film or an anti-reflective coating for aresist film, and the heat processing sequence performs the heat processon the target film.
 9. A computer readable non-transitory storage mediumthat stores a control program for a heat processing apparatus, whichincludes a heating plate configured to support and heat a substrate, acover configured to surround a space above the heating plate, a firstgas flow forming mechanism configured to form first gas flows within thespace above the heating plate, the first gas flows being downward flowsof gas uniformly supplied onto an upper surface of the substratesupported by the heating plate, a second gas flow forming mechanismconfigured to form second gas flows within the space above the heatingplate, the second gas flows being sideward flows of gas along the uppersurface of the substrate supported by the heating plate, and a controlmechanism configured to control an operation of the apparatus andincluding a computer, wherein the control program, when executed, causesthe computer to control the apparatus to conduct a heat processingsequence, which comprises: supporting a target substrate by the heatingplate to heat the target substrate and surrounding the space above theheating plate by the cover; and then performing a heat process on thetarget substrate by heating the target substrate by the heating plate,wherein the heat process is performed along with first and second modesof gas flows sequentially set in this order while heating the targetsubstrate by the heating plate, the first mode uses the downward flowsformed by the first gas flow forming mechanism to uniformize the heatprocess over the target substrate, and the second mode uses the sidewardflows formed by the second gas flow forming mechanism while exhaustinggas from the space above the heating plate to exhaust and remove atleast one of gas and sublimed substances generated from the targetsubstrate.
 10. The storage medium according to claim 9, wherein thesecond mode uses the sideward flows such that gas is caused to flow froma periphery of the target substrate toward a center thereof and then tobe exhausted upward from the center.
 11. The storage medium according toclaim 9, wherein the second mode uses the sideward flows such that gasis caused to flow from one side of the target substrate toward anopposite side thereof and then to be exhausted from the opposite side.12. The storage medium according to claim 10, wherein the first modeuses the downward flows such that gas is caused to flow from above ontothe target substrate and then to be exhausted toward a periphery of thetarget substrate.
 13. The storage medium according to claim 11, whereinthe first mode uses the downward flows such that gas is caused to flowfrom above onto the target substrate and then to be exhausted toward aperiphery of the target substrate.
 14. The storage medium according toclaim 9, wherein the cover includes a number of gas delivery holesformed in a counter plate facing the heating plate and communicatingwith a gas diffusion space that pools a purge gas, periphery exhaustports opened at positions around the heating plate, a center exhaustport opened at a center of the counter plate and connected to an exhaustpipe, and gas intake ports opened at positions around the heating plate,such that the first gas flow forming mechanism forms the downward flowsby supplying the purge gas from the gas delivery holes toward thesubstrate supported by the heating plate while exhausting gas on thesubstrate from the periphery exhaust ports, and the second gas flowforming mechanism forms the sideward flows by introducing gas from thegas intake ports while exhausting gas on the substrate supported by theheating plate from the center exhaust port.
 15. The storage mediumaccording to claim 9, wherein the cover includes a number of gasdelivery holes formed in a counter plate facing the heating plate andcommunicating with a gas diffusion space that pools a purge gas;periphery exhaust ports opened at positions around the heating plate; aside delivery port opened at a position on one side around the heatingplate, and a side exhaust port opened at a position on an opposite sidearound the heating plate, such that the first gas flow forming mechanismforms the downward flows by supplying the purge gas from the gasdelivery holes toward the substrate supported by the heating plate whileexhausting gas on the substrate from the periphery exhaust ports, andthe second gas flow forming mechanism forms the sideward flows bysupplying gas from the side delivery port toward the substrate supportedby the heating plate while exhausting gas on the substrate from the sideexhaust port.
 16. The storage medium according to claim 9, wherein thetarget substrate includes a target film formed thereon and including aresist film or an anti-reflective coating for a resist film, and theheat processing sequence performs the heat process on the target film.